Silencer



July 1s, 1939. R, L. HQYLE l 2,166,408

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Patented July 18, 1939 SILENCER Robert L. Hoyle, Lombard, 11i., assigner to nur gess Battery Company, Chicago, Ill., a corporation lof 'Wisconsin Application September l, 1938, Serial No. 227,951

(ci. 1an-5s) 'l' Claims.

The present invention relates to silencers and particularly to silencers for quieting, the exhausts 'and intakes of internal combustion engines.

It is the object of the invention to provide an improved silencer which possesses high silencing eectiveness and offers little restriction to Ythe :ow of gases therethrough, and which is of simple and economical construction.

The silencer of this invention is related to the combined silencer` and spark arrester of my copending application Serial No. 197,193, filed March 21, 1938, and also to the silencer disclosed and claimed in the co-pending application of my co-worker Willis L. Manning, Serial No. 216,856, filed July 1, 1938. Briefly, it relates to aslencer of the retroverted passage type in which conduits are provided for the inlet and outlet passages but none are provided for the intermediate passage between these two, the sounds and gases being free/tp employ the entire space within the silencer chamber for this passage. Such construction is simple and yet highly effective for the silencing function, and it has an advantage peculiar to itself of not requiring a ltail pipe of appreciable length to be connected to the outlet. In the more recent silencers which do not employ bailles to accomplish the silencing function, it has been found necessary to employ a tail pipe of appreciable length to obtain what is called a loading effect upon the silencer. Besides representing an expense, such a tail pipe, in many applications because of space requirements, is inconvenient or impractlcable. In such situations the present type of silencer is of particular value.

In the said co-pending Manning application, a silencer is disclosed in which the inlet and outlet conduits are perforated. I have discovered that it is not necessary that both of them be perforated, but'that one of them may be imperforate, or solid walled. The silencing eectiveness is not impaired by the use of a solid walled tube at one end of the chamber, and it represents a simpliilcation and economy in construction. Such construction also facilitates the adjustment of the frequency response of the silencer, that is, the

sound frequencies for which it is ell'ective. This' may be varied to some extent by varying the pro-v portion of the conduit walls occupied by the perforations thereof, and where the conduits ex.

tending from one end of the silencer only are perforated the control of the frequency response is simplified. 'Ihe manufacturing operations are simplified also, since the use of solid conduits avoids the perforating operation.

In the drawing:

, Fig. -l is a longitudinal sectional view of one form of the silencer of this invention; I

Fig. 2 is a transverse sectional vieur along line 2-2 of Fig.1; Figs. 3 and 4 and 5' are longitudinal sectional l views of modifications of the silencer of this invention; and A 6 is a transverse sectional view along line i-t of Fig. `5.

The silencer of Figs. l and 2 comprises an iinperforate casing Iii, closed at its ends by end walls II and l2. Said end walls have inlet opening I3 and outlet opening I4 therein respectively, said openings being displaced laterally with respect to each other and to the center line of the silencer. E@ Perforated, open-ended inlet tube I5 is mounted in inlet opening I3'and extends into the chamber toward the opposite end wall I2, the inner end stopping in spaced relation to said end wall I2. Solid walled, open-ended outlet tube IS is g@ mounted in outlet opening I4 and extends into the chamber toward the opposite end wall I I, the interior end thereof. being spaced from the inlet end Wall III in the same manner as the end of inlet tube I5 is spaced from outlet end wall I2. u The two tubes are arranged in juxtaposed relation within the chamber and extend laterally adjacentv each other throughout a large proportion of their length. The perforations or openings in the tube I5 in this form of the invention,- as well 3o as the perforations or openings in the perforated tubes of the modifications Which will be described hereinafter, may be other than round and may be larger or smaller than shown.

In operating the silencer for silencing the exas haust of an internal'combustion engine, the inlet y tube I5 is connected to the exhaust pipe of the internal combustion engine and the exhaust gases enter at inlet opening I3, pass through tube I5 and emerge from the end of said tube where they 40 expand into the relatively large area of the space vWithin the chamber enclosed by casing Ill. and

reverse their direction and travel forwardly in said chambervto the open end of solid walled outlet tube I6, and thence through outlet tube It 46' and outlet opening I6 and out of the silencer.

e major proportion ofthe gases follows the path just described; while a minor proportion passes laterally through the perforations or openings of inlet tube I5 and follow a shorter path 50 forwardly to 'the open end of outlet tube i6. There is also an impingement of. the gases against end walls I2 and II as they undergo reversalf direction at the ends of the silencer. The gases y pass laterally through the openings of inlet tube' I in quantities proportional to the pressure dif-g ference existing between the inside and the outside of the tubes. .It is understood that in the exhaust of an internal combustion engine pulses tenuate both the high and low pressure conditions inside and outside of the tube and cause a general smoothing of the stream. 'I'he silencer is highly effective over the range which is important in internal combustion engine' silencing, and it has been found that in many instances a smaller silencer may be used than is customary.

In Fig. 3 a modification of the invention is shown which is adapted for those applications in which concentricinlet and -outlet silencer openings are desirable. In this modification the relativearrangement of the tubes is reversed, in that the inlet tube, instead of the outlet tube, is solid and the outlet tube is perforated. It has been found that the silencer is substantially equally effective with either arrangement. The silencer comprises imperforate casing 20 having inlet end wall-2| and outlet end Wall 22,

' said end walls having inlet opening 23 and outlet opening 24 therein, in which are mounted the tube connections 25 and 26. A transverse partition 21 extends across the interior of cas.- ir'ig 20 at a point adjacent and spaced inwardly from inlet end wall 2|. In a similar manner, a second partition 28 extends across the casing at a point spaced inwardly from outlet end wall 22. Partitions 21 and 28 subdivide the casing into a silencing chamber 29 and two end chambers 3l and 32. Partitions 21 and .28 have openings 33`and 34 therein, said openings being displaced laterally with respect to each other and to the center line of the silencer. A solid, open-ended inlet tube is mounted at one end in opening 33 of partition 21 and extends into silencing chamber 29 part way toward the opposite partition 28, and perforated, open-ended outlet tube 36 is mounted in a similar manner in opening 34 of partition 28 and extends into the chamber part way toward partition 21. Tubes 35 and 36 are arranged in juxtaposed relation and extend laterally adjacent each other throughout a, large portion of their length within chamber 29.

When using this construction as an exhaust silencer, the exhaust gases enter tube connection 25 and pass into chamber 3i where they strike the central solid portion of partition 21 and then spread laterally and converge and pass into solid walled inlet tube 35, through this tube and thence through the interior space of chamber 29 to perforated tube 36, the action being similar to. that described in connection with Figs. 1 and 2, except that there is a lateral iow of gases and sound`through the walls of the outlet tube instead of the inlet tube. The gases emerging from outlet tube 36 impinge against the solid portion of the casing outletwall 22 opposite the said tube 36, and then spread laterally and pass out of the silencer through outlet tube connection 26.

The modification illustrated in .FigA is similar `to that of Figs.'1`and 2 but hasseveral additional sound attenuating chambers in which the attenuation is accomplished by means of resonators and porous sound-absorbing and gas-pressure-absorbing material. It comprises an imperforate casing 40 having end walls 4l and 42 and. intermediate partitions 43 and 44 subdividing the casing into direction-reversing chamber and two additional chambers 46 and 41. End Wall 4| has an inlet opening 48 therein, and outlet end wall 42 has4 an outlet opening 49 therein, and intermediate partitions 43 and 44 have openings 50 and 5I therein aligned with outlet opening 49.4 'I'he inlet opening 48'and the outlet opening 49 are displaced laterally with respect to each other and to the center line of the silencer. Perforated inlet tube 53 is mounted in inlet opening 49 and extends into direction-reversing chamber 45 in the same manner as described heretofore in connection with Figs. l, 2 and 3, and solid outlet tube 54 is mounted in the opening 50 of partition 43 and extends into the chamber 45, said outlet tube 54 continuing through chambers 46 and 41. The portion Within chamber 46has one or more openings 55 therein serving to connect the space within chamber 46 to the tube in sidebranch relation to form a resonator construction. The portion passing through chamber 41 is perforated, and this chamber is filled with porous sound-absorbing and gas-pressure-absorbing material 56 which exerts an attenuating effect upon the sound and gas pressure pulses passing through the tube 54 in the well-known manner.

In Figs. 5 and 6 a modification of the invention is illustrated in-which there are two inlet tubes and two outlet tubes. The imperforate casing 60 has inletv end wall 6I and outlet end wall 62 to form a single-silencing chamber. The perforated open-ended inlet tubes 63 are mounted in openings in the inlet end wall 6I and extend into the chamber to a point adjacent and spaced from outlet end wall 62, and in a similar manner solid outlet tubes 64 are mounted in openadjacent and spaced from inlet end wall 6I.

I'he action of this silencer is similar to that of those described heretofore, this form being particularly adapted for the silencing of an internal combustion engine having two exhaust lines. It is understood that the silencer may have more than two inlet and outlet tubes, and that it may have any desired combination of inlet and outlet tubes, such as two inlet tubes and one outlet tube, or vice versa.

In the silencer `of this invention it has been found that the area of the openings or perforations in the walls of the perforated tube or tubes may be varied within limits between approximately 0.03% and 10% of the total area of said walls. As has been stated heretofore, variation of the opening area within this range changes the performance characteristics of the silencer by varying the frequency response, and, therefore, the opening'area may be varied to secure the best performance for the particular application.

While the action of the silencer has been described in connection with its usefor the silencing of the exhausts of internal combustion engines, it is adapted as well for the silencing of intakes. There are some differences in the nature of the sounds and `gas pulses which are encountered in the two applications. In exhaust silencing the sounds and pulses of gas at high temperature movein the same direction while in intake silencing the sounds move outwardly atively low temperature move inwardly. The silencer of this invention attenuates with equal effectiveness in both cases.

I claim: J 1. A silencer comprising means forming a chamber, said chamber having inlet and outlet openings in opposite walls thereof, open-ended inlet and outlet conduits arranged in juxtaposed relation within said chamber, said inlet and outlet conduits being connected at one end thereof to said inlet and outlet openings, respectively, and each extending from the wall opening to which it is connected part way toward the opposite wall and having an open end located within said chamber, said inlet and outlet conduits being arranged laterally adjacent one another throughouta portion of their length, the open ends of said conduits located within vsaid chamber being in free and unconned communication with each other through the space Within said chamber, the conduitl extending from one wall of said chamber having imperforate walls, and the I conduit extending from the other chamber wall having openings in the Walls thereof. 2. A silencer comprising means forming a chamber, said chamber having at least one open- I ended inlet tube mounted in one wall thereof and `at least one open-ended outlet tube mounted in the opposite wall thereof, said inlet and outlet 3o tubes being arranged in juxtaposed relation within said chamber and each extending from the wall in which it is mounted into said chamber` part way toward the opposite wall, said inlet and outlet tubes being arranged laterally adjacent one another throughout a portion of their length, the open end of said tubes located within said chamber being in free and unconned communication with each other through the space withinsaid chamber, the tube extending from one cham- V4() bert/wall having its walls imperforate, and the tube extending from the opposite chamber Wall having openings in the walls thereof.

3. A silencer comprising means forming a chamber, said chamber having inlet and outlet 45 openings in opposite walls thereof, open-ended inlet and outlet tubes mounted in said inlet and outlet openings respectively, said inlet and outlet tubes being arranged in juxtaposed relation within said chamber and each extending from 50 the wall opening in which it is mounted into said chamber part way toward the opposite wall and ending in adjacent spaced relation to said opposite wall, said inlet and outlet tubes being arranged laterally adjacent one another throughu out a portion of their length, the open ends of said tubes located within said chamber being in free and unconned communication-with each other through the space within said chamber, the

ing from the Opposite chamber wall having openings in the walls thereof.

4. The silencer of claim 1 in which the openings in lthe conduit having openings in the walls thereof occupy approximately 0.03%v to 10% of 5l the total area of the walls of said conduits.

5` A silencer comprising a substantially imperforate casing having inlet and outlet openings therein, at least one transverse partition within said casing providing a chamber within 10 said casing, open-ended inlet and outlet tubes mounted in opposite walls of said chamber and communicating with said inlet and outlet openings respectively, said tubes being oifset lateral ly with respect to each other and'each extending 15 from the wall in which it is mounted into said chamber part way toward the opposite wall of said chamber and ending in adjacent, spaced relation to saidl opposite wall, said oppositely extending tubes being arranged laterallyv adjacent 20 -one another throughout a portion of their length and being directly exposed to one, another, the open ends of said tubes located'within said chamber being in free and -unconi'lned communication with each other through the space within said 25 chamber, the tube extending from one wall of said chamber having imperforate walls and the tube extending from the opposite Wall of said chamber having perforated walls.

6. The silencer of claim 5 in which at least 30v one chamber wall has a pluralityof openings therein and a tube is mounted in each of said openings and extends toward but stops short of the opposite chamber wall.

7. A silencercomprising a substantially im- 35 perforate casing having inlet and outlet openings in opposite end Walls thereof respectively, and having at least one transverse partition therein subdividing said casing into a plurality of chambers, one of said chambers having inlet and out- 40 let openings in opposite Walls thereof, openended inlet and outlet tubes arranged in. juxtaposed relation within said chambers, said inlet and voutlet tubes being connected at one end thereof to said inlet and outlet openings of said chamber respectively, and each extending inwardly from the wall opening to which it is connected part way toward the opposite wall of said chamber said inlet and outlet tubes being arranged laterally adjacent each other throughout a portion of their length, the tube extending from one chamber wall having its walls irnperforate, and the tube extending from the opposite chamber Wall having openings in the walls thereof, and conduit means passing through the remainder -of i515 -the chambers in said casing and connecting said tubes with said casing openings, and sound attenuating means -in said additional chambersin- Vcooperative relation with, said conduit means.

.ROBERT L. HOYLE. 

